Security is brought back in warehouse (7)
I believe the answer is:
deposit
'security' is the definition.
(I know that deposit is a type of security)
'is brought back in warehouse' is the wordplay.
'brought back' shows that the letters should be reversed in order.
'in' is an insertion indicator.
'warehouse' becomes 'depot' (I've seen this in another clue).
'is' reversed gives 'si'.
'si' put into 'depot' is 'DEPOSIT'.
(Other definitions for deposit that I've seen before include "Hoard" , "part-payment" , "Money given as security" , "Put down or leave something" , "(Money) laid down" .)